That SQL/NoSQL are "two sides of the same coin" does not mean, as you seem to imply, that they are the same SIDE. Two sides means that they are opposite ends. Thus, each has different (actually complimentary) pros/cons.
Which is exactly what the phrase you quote implies: that normalization incurs some damage that we have to undo (via O/R mapping in the example given), if we want to get the same pros of a NoSQL solution from a SQL datastore.
Somehow inconsistent with the idea that SQL and NoSQL are two sides of the same coin, mathematically.....